1. Field of the Invention
Embodiments of the present invention generally relate to a novel seal assembly for use in a wellbore tool. An upper end of the seal assembly acts as a flow restrictor protecting a lower end of the seal assembly from high pressure and/or high volume flow.
2. Description of the Related Art
Subsequent to the drilling of an oil or gas well, it is completed by running into such well a string of casing which is cemented in place. Thereafter, the casing is perforated to permit the fluid hydrocarbons to flow into the interior of the casing and subsequently to the top of the well. Such produced hydrocarbons are transmitted from the production zone of the well through a production tubing or work string which is concentrically disposed relative to the casing.
In many well completion operations, it frequently occurs that it is desirable, either during the completion, production, or workover stages of the life of the well, to have fluid communication between the annular area between the interior of the casing and the exterior of the production tubing or workstring with the interior of such production tubing or workstring for purposes of, for example, injecting chemical inhibitor, stimulants, or the like, which are introduced from the top of the well through the production tubing or workstring and to such annular area. Alternatively, it may be desirable to provide such a fluid flow passageway between the tubing/casing annulus and the interior of the production tubing so that actual production fluids may flow from the annular area to the interior of the production tubing, thence to the top of the well. Likewise, it may be desirable to circulate weighting materials or fluids, or the like, down from the top of the well in the tubing/casing annulus, thence into the interior of the production tubing for circulation to the top of the well in a “reverse circulation” pattern.
In instances as above described, it is well known in the industry to provide a well tool having a port or ports therethrough which are selectively opened and closed by means of a “sliding” sleeve element positioned interiorly of the well tool. Such sleeve typically may be manipulated between open and closed positions by means of wireline, remedial coiled tubing, electric line, or any other well known auxiliary conduit and tool means.
Typically, such ported well tools will have upper and lower threaded ends, which, in order to assure sealing integrity, must contain some sort of elastomeric or metallic sealing element disposed in concert with the threads to prevent fluid communication across the male/female components making up the threaded section or joint. A placement of such a static seal represents a possible location of a seal failure and, as such, such failure could adversely effect the sealing integrity of the entire production tubing conduit.
Additionally, in such well tools, a series of upper and lower primary seals are placed in the housing for dynamic sealing engagement relative to the exterior of a sleeve which passes across the seals during opening and closing of the port element. As with all seals, such primary sealing means also represent an area of possible loss of sealing integrity.
During movement of the sleeve to open the port in such well tool to permit fluid communication between the interior and exterior thereof, such primary seals positioned between the interior wall of the well tool housing and the exterior wall of the shifting sleeve will first be exposed to a surge of fluid flow which can cause actual cutting of the primary seal elements as pressure is equalized before a full positive opening of the sleeve and, in some instances, during complete opening of the sleeve. In any event, any time such primary seals are exposed to flow surging, such primary seals being dynamic seals, a leak path could be formed through said primary seals.
Accordingly, there is a need for a well tool wherein the leak paths are reduced, thus greatly reducing the chances of loss of sealing integrity through the tool and the tubular conduit. Secondly, there is a need for a well tool in which sensitive areas of the primary seal element are protected by substantially blocking fluid flow thereacross during shifting of the sleeve element between open and closed positions.
The present invention generally relates to a novel seal assembly for use in a wellbore tool. An upper end of the seal assembly acts as a flow restrictor protecting a lower end of the seal assembly from high pressure and/or high volume flow.
In one aspect, a tool for use in a wellbore is provided, comprising a tubular housing having a bore therethrough and at least one flow port disposed through a wall thereof; a sleeve slidably mounted within the housing, wherein the sleeve has a bore therethrough and at least one flow slot disposed through a wall thereof, the at least one slot selectively alignable with the at least one flow port; and a seal assembly disposed between the housing and the sleeve, wherein the seal assembly is configured so that a first portion of the seal assembly protects a second portion of the seal assembly from substantial damage during actuation of the tool. Preferably, the seal assembly comprises a center adapter. Preferably, either the length of the center adapter or that of the seal assembly substantially corresponds to the length of the sleeve flow slot and the center adapter comprises a plurality of protrusions disposed around both an inner side and an outer side thereof. Preferably, the seal assembly further comprises a first end adapter; a second end adapter, wherein the center adapter is disposed between the two end adapters; at least one first sealing element disposed between the first end adapter and the center adapter; and at least one second sealing element disposed between the second end adapter and the center adapter.
In another aspect, a seal assembly for use in a wellbore tool is provided, comprising a first end adapter; a second end adapter; a center adapter disposed between the two end adapters; at least one first sealing element disposed between the first end adapter and the center adapter; and at least one second sealing element disposed between the second end adapter and the center adapter, wherein the length of the seal assembly substantially corresponds to a length of a sleeve flow slot of the wellbore tool. Preferably, a plurality of protrusions are disposed around both sides of the center adapter.
In yet another aspect, a seal assembly for use in a wellbore tool is provided, comprising a tubular housing having a bore therethrough and at least one flow port disposed through a wall thereof; a sleeve slidably mounted within the housing, wherein the sleeve has a bore therethrough and at least one flow slot disposed through a wall thereof, the at least one slot selectively alignable with the at least one flow port; and a seal assembly comprising a center adapter, wherein the center adapter includes a structure configured for limiting fluid flow across the seal assembly during actuation of the tool.
In yet another aspect, a method of using a wellbore tool is provided, comprising providing the wellbore tool, wherein the tool comprises a tubular housing having a bore therethrough and at least one flow port disposed through a wall thereof; a sleeve slidably mounted within the housing, wherein the sleeve has a bore therethrough and at least one flow slot disposed through a wall thereof; and a seal assembly disposed between the housing and the sleeve; running the wellbore tool into a pressurized wellbore; and sliding the sleeve over the seal assembly, wherein a first portion of the seal assembly will restrict flow of pressurized fluid to a second portion of the seal assembly so that the second portion is not substantially damaged during sliding of the sleeve.
In yet another aspect, a method of using a wellbore tool is provided, comprising providing the wellbore tool, wherein the tool comprises a tubular housing having a bore therethrough and at least one flow port disposed through a wall thereof; a sleeve slidably mounted within the housing, wherein the sleeve has a bore therethrough and at least one flow slot disposed through a wall thereof; a seal assembly comprising a center adapter, wherein the center adapter includes a structure; running the wellbore tool into a pressurized wellbore; and sliding the sleeve over the seal assembly, wherein the structure of the center adapter will limit fluid flow across the seal assembly so that the seal assembly is not substantially damaged during sliding of the sleeve.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
Three retainer grooves: upper groove 35, middle groove 30, and lower groove 25 are formed in a wall on an inner side of the lower housing 5. The three grooves 25, 30, and 35 correspond to the three positions of the tool 1: closed, equalization, and open, respectively. A latch 20 is formed integrally with and extends outward from a lower side of the sleeve 15. In
Formed proximately below the groove 25 in the lower housing 5 is a shoulder. A corresponding shoulder (see
Referring now to
Disposed through a wall of the sleeve 15 are a flow port 45 and an equalization port 50. Both ports 45 and 50 comprise a series of slots disposed around the sleeve 15. The slots of the equalization port 50 are smaller in comparison to the slots of the flow port 45. Thus, under the same pressure the flow capacity of the equalization port 50 is less than that of the flow port 45.
The adapters 55a,e,i may be made of any substantially hard nonelastomeric material, such as a thermoplastic polymer, or they may be made of metal. Examples of a suitable thermoplastic polymer are Polyetheretherkeytone (PEEK), PEK, PEKK, or any combination of PEEK, PEK, and PEKK. The sealing elements 55b-d and 55f-h may also be made of a thermoplastic polymer or they may be made of an elastomer. Preferably, the adapters 55a,e,i are constructed from a relatively hard material as compared to a preferable soft material of the sealing elements 55b-d and 55f-h. Examples of the relatively soft material are TEFLON (Du-Pont Trademark) and rubber.
The adapters 55a,e,i comprise protrusions 55j-m. The center adapter 55e has been narrowed and the protrusions 55k,l have been exaggerated for the purpose of illustration. Each protrusion is disposed around both an inner side and an outer side of the adapters 55a,e,i. Preferably, the protrusions 55j-m are formed such that their cross-sections are substantially in the shape of a right-triangle, however, other cross-sectional shapes will suffice. The protrusions 55j,k are oriented such that the hypotenuse of each faces the upper end of the tool. Conversely, the protrusions 551l-m are oriented such that the hypotenuse of each faces the lower end of the tool. However, any orientation of the protrusions 55j-m should suffice. Alternately, the protrusions 55j-m may be disposed around only one side of the adapters 55a,e,i. If the adapters 55a,e,i are constructed from metal, protrusions 55j-m may be disposed as separate softer pieces within grooves (not shown) formed in the adapters 55a,e,i. A preferred configuration of seal assembly 55 is shown, however, the number of protrusions may be varied according to the design requirements of the seal assembly. Also, protrusions may be disposed around only the end adapter 55a or around only the center adapter 55e. Further, there may be no protrusions at all. The secondary seal assembly 85 may be a conventional packing stack which is well known in the art so it will not be discussed in detail.
Operation of the tool 1 is as follows. Referring to
At some point, it will be desired to actuate the sleeve 15. As the sleeve is being actuated from the closed position (
The length of the center adapter 55e corresponds substantially to that of the flow port 45. However, the length of the center adapter 55e may be substantially longer or shorter than that of the flow port 45. If a shorter center adapter 55e is desired, more sealing elements may be added so that the overall length of the seal assembly 55 at least substantially corresponds to that of the flow port 45. The correspondence in length between the center adapter 55e and the flow port 45 ensures the protective members 55a-e of the seal assembly 55 are in position to shield the members 55f-h from high pressure and/or high volume flow during the transition between the closed and equalization positions of the tool 1.
The seal assembly 55 is shown in wellbore tool 1. However, the seal assembly 55 may be disposed in different tools that serve varying functions in the drilling and completion of a wellbore.
Referring to
It will be appreciated that the apparatus of the present invention may be incorporated on a production string during actual production of the well in which the wellhead 200 will be in the position as shown. Alternatively, the apparatus of the present invention may also be included as a portion of a workstring during the completion or workover operation of the well, with the wellhead 200 being removed and a workover or drilling assembly being positioned relative to the top of the well.
As shown in
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
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